In U.S. Pat. No. 5,059,166 by R. E. Fischell et al there is described a thin wire with a radioactive tip, which tip can be inserted within an artery of a human subject to irradiate a section of that artery that has been treated with balloon angioplasty. The purpose of that radiation is to decrease the rate of restenosis at the treatment site. A significant disadvantage of a thin wire that is not centered in the artery is that the side of the artery that is touched by the wire will experience a much higher dose of radiation as compared to the opposite side of the artery.
In the same U.S. Pat. No. 5,059,166 by R. E. Fischell et al, there is also described a radioisotope stent that is permanently placed at the site of a stenotic dilatation. Although the radioisotope stent is accurately centered in the artery, animal testing has shown that the permanently implanted radioisotope stent can cause the formation of an acellular matrix within the stent that can result in restenosis.